diff --git a/naive-nlu/tree_nlu/knowledge_base.py b/naive-nlu/tree_nlu/knowledge_base.py
index 830a6f3..b34efe7 100644
--- a/naive-nlu/tree_nlu/knowledge_base.py
+++ b/naive-nlu/tree_nlu/knowledge_base.py
@@ -3,6 +3,7 @@ import logging
 
 from .session.org_mode import global_session as session
 
+from .atoms import Atom
 from . import parsing
 from . import knowledge_evaluation
 from .modifiable_property import is_modifiable_property
@@ -20,6 +21,7 @@ class KnowledgeBase(object):
         self.examples = copy.copy(examples)
         self.trained = copy.copy(trained)
         self.tokenization = set()
+        self.structural_elements = set()
 
     def train_tokenizer(self, example):
         with session().log('Train'):
@@ -74,6 +76,14 @@ class KnowledgeBase(object):
                 return parsing.pick_one_tokenization(options)
             return options
 
+    def add_tokenization(self, tokenization):
+        with session().log('Added tokenization: “{}”'.format(tokenization)):
+            self.tokenization.add(tokenization)
+            for e in tokenization:
+                if (not isinstance(e, Atom)) and (e not in self.structural_elements):
+                    session().annotate('Found new structural element “{}”'.format(e))
+                    self.structural_elements.add(e)
+
     def process(self, row):
         knowledge_before = copy.deepcopy(self.knowledge)
         with session().log("Process: {}".format(row)):
diff --git a/naive-nlu/tree_nlu/parsing.py b/naive-nlu/tree_nlu/parsing.py
index 6cae405..198bda2 100644
--- a/naive-nlu/tree_nlu/parsing.py
+++ b/naive-nlu/tree_nlu/parsing.py
@@ -99,7 +99,7 @@ def integrate_token_to_text_matching(knowledge_base, text, tokens):
             elements.append(texts[i])
             i += 1
 
-        knowledge_base.tokenization.add(tuple(elements))
+        knowledge_base.add_tokenization(tuple(elements))
 
 def pick_one_tokenization(options):
     '''